The rapid development and rich service operation modes of modern wireless communication technologies invigorate mobile communication networks. Conventional mobile communication networks can hardly meet people's requirements for high capacity, high transmission rate, and high reliability. Therefore, upgrading the existing mobile communication networks is an unavoidable trend. Nowadays, the worldwide wireless networks need innovations urgently. For the GSM (Global System for Mobile Communication, Global System for Mobile Communication) network having numerous mobile users, the focus of the upgrade of mobile communication networks is ultimately the upgrade of the GSM network, which has a wide prospect of market application in the future mobile broadband field. In view of the investment protection and user habits of the existing massive GSM network, the future mobile network is a GSM-based converged wireless network that supports multiple wireless standards. In a converged network of the GSM and LTE (Long Time Evolution, Long Time Evolution), if the GSM system and the LTE system share antennas, the cost may be greatly reduced. However, when the GSM system and the LTE system share antennas, the problem of severe inter-cell interferences occurs.
In the prior art, a method for solving the problem of inter-cell interferences that occurs when the GSM system and the LTE system share antennas is as follows: an antenna element of a current cell and an antenna element of a neighboring cell transmit one same signal to a mobile terminal at the same time and at the same frequency, in which, for the terminal, the antenna element of the current cell and the antenna element of the neighboring cell serve the terminal together, which is equivalent to that the interference signal transmitted by the antenna element of the neighboring cell is converted into a serving signal, which therefore reduces the interferences between cells. In this case, the antenna element of the current cell and the antenna element of the neighboring cell serve the mobile terminal together. Therefore, the antenna element of the current cell and the antenna element of the neighboring cell form a cell, and the cell is a common cell. FIG. 1 is an architecture diagram of a common cell formed of cells that include multiple antenna elements. Further, FIG. 2-a is a schematic diagram of a terminal being interfered before multiple antenna elements combine into a common cell in the prior art. As shown in FIG. 2-a, the arrow indicates an antenna element with a unidirectional antenna, and the circle indicates an antenna element with an omnidirectional antenna. For terminal A, antenna element 3 in the cell that covers terminal A is a serving antenna element. Therefore, antenna element 3 transmits a serving signal, and antenna elements 1, 2, 4, 5, 6, 7, and 8 of other neighboring cells all transmit interference signals. For terminal B, antenna element 6 in the cell that covers terminal B is a serving antenna element. Therefore, antenna element 6 transmits a serving signal, and antenna elements 1, 2, 3, 4, 5, 7, and 8 of other neighboring cells all transmit interference signals. FIG. 2-b is a schematic diagram of a terminal being interfered after multiple antenna elements combine into a common cell in the prior art, and after antenna elements 1, 2, 7, and 3 combine into a common cell and antenna elements 4, 5, 6, and 8 combine into a common cell, for terminal A, antenna elements 1, 2, 7, and 3 all transmit serving signals; for terminal B, antenna elements 4, 5, 6, and 8 all transmit serving signals. Although the foregoing method reduces inter-cell interference signals in the amount, for terminal A, antenna elements 4, 5, 6, and 8 still transmit interference signals; also, for terminal B, antenna elements 1, 2, 7, and 3 still transmit interference signals. Moreover, each terminal is served by multiple antenna elements at the same time. Such “excessive serving” also leads to the problem of waste of system resources.
To further overcome the problem in the foregoing method, another method in the prior art is as follows: after multiple antenna elements combine into a common cell, a terminal measures the channel quality of each antenna element in the common cell during signal transmission and feeds back the channel quality to the base station, and the base station selects a serving antenna element for the terminal according to the feedback information, and other antenna elements that are not selected do not transmit signals to the terminal. FIG. 3 is a schematic diagram of a terminal being interfered after multiple antenna elements combine into a common cell and an antenna element is selected in the prior art. For terminal A, the base station selects, according to the channel quality, from antenna elements 1, 2, 7, and 3 in the common cell, antenna element 3 as an antenna element capable of binding terminal A (namely, antenna element 3 is capable of serving terminal A). Likewise, for terminal B, the base station selects, according to the channel quality, from antenna elements 4, 5, 6, and 8 in the common cell, antenna element 6 as an antenna element capable of binding terminal B (namely, antenna element 6 is capable of serving terminal B). In this way, for terminal A, because antenna elements 4, 5, and 8 do not transmit signals, only antenna element 6 transmits interference signals; also, for terminal B, only antenna element 3 transmits interference signals. Moreover, each terminal is only served by one antenna element, which avoids the problem of resource waste caused by “excessive serving”.
However, in the research process, the inventor of the present disclosure finds that the antenna selection solution after multiple antenna elements combine into a common cell has the following disadvantages. FIG. 4-a is a schematic diagram of terminal A being interfered when the base station receives channel quality information fed back by the terminal in the prior art. As shown in FIG. 4-a, the base station selects, according to the feedback channel quality information, antenna element 3 as a binding antenna element for terminal A; meanwhile, terminal A is interfered by interference signals transmitted by antenna element 6 of the neighboring cell. FIG. 4-b is a schematic diagram of terminal A being interfered when the base station begins to serve terminal A in the prior art. After a period, the base station begins to serve terminal A by delivering data to terminal A. At this time, terminal A and the PDSCH (Physical Downlink Shared Channel, physical downlink shared channel) are interfered by interference signals transmitted by antenna element 4 of the neighboring cell. Therefore, the interferences are changed from the time that terminal A sends the channel quality information, and the signal to interference plus noise ratio of the PDSCH is not equal to the signal to interference plus noise ratio in the channel quality information, namely, the interference fluctuates. Evidently, when the terminal feeds back the channel quality information to the base station and when the base station begins to serve terminal A, terminal A is interfered by signals transmitted by different antenna elements of the neighboring cell, which leads to interference fluctuation.